Abstract
Tensegrity structures are structures composed of uniaxially loaded members in a self-equilibrated state. Tensegrity structures have been proposed for civil engineering applications, such as roofs, platforms, buildings, and bridges, as well as aerospace structures such as planetary landers, autonomous robots and deployable antennas. However, tensegrity structures are still not part of the mainstream structural engineering design. Therefore, this study focused on the axial mechanical behavior and deployment of a linear assembly of simplex modules. Composed of three struts and nine cables, simplex represents the most elementary three-dimensional tensegrity structure. Dynamic relaxation is employed to investigate the structural response of a selected series of simplex module assemblies under vertical load and folding/unfolding. Dynamic relaxation is an explicit numerical form-finding and structural analysis method for tensile structures, such as tensegrity systems. The method is based on the fact that the static solution for a structure subject to loading is the steady state of a step-force damped vibration. Parametric analyses on the influence of element stiffness on the axial response and the actuation step (changes in element lengths that guide shape transformations) were also conducted to assess the sensitivity of the systems to errors and actuation. The analyses revealed that prestress, an inherent characteristic of tensegrity structures, is critical for the axial stiffness of the system decreasing and distributing the effect of vertical loads in the assemblies studied. Moreover, actuation step and the relative step ratio between vertical and horizontal cables was found to be critical for controlling the folding/unfolding shape transformation as well as the forces developed during this phase. These findings highlight that if appropriately designed, the resulting deployable tensegrity structures can be both structurally as well as adaptively efficient.